docs/devel/tcg-plugins: added cores arg to cache plugin

Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Message-Id: <20210803151301.123581-3-ma.mandourr@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

docs/devel/tcg-plugins.rst

@@ -355,11 +355,8 @@ configuration when a given working set is run::
 
 will report the following::
 
-    Data accesses: 996479, Misses: 507
-    Miss rate: 0.050879%
-
-    Instruction accesses: 2641737, Misses: 18617
-    Miss rate: 0.704726%
+    core #, data accesses, data misses, dmiss rate, insn accesses, insn misses, imiss rate
+    0       996695         508             0.0510%  2642799        18617           0.7044%
 
     address, data misses, instruction
     0x424f1e (_int_malloc), 109, movq %rax, 8(%rcx)
@@ -403,3 +400,9 @@ The plugin has a number of arguments, all of them are optional:
   Sets the eviction policy to POLICY. Available policies are: :code:`lru`,
   :code:`fifo`, and :code:`rand`. The plugin will use the specified policy for
   both instruction and data caches. (default: POLICY = :code:`lru`)
+
+  * arg="cores=N"
+
+  Sets the number of cores for which we maintain separate icache and dcache.
+  (default: for linux-user, N = 1, for full system emulation: N = cores
+  available to guest)